This is maybe not a bug, strictly speaking: I've noticed on my mag blade that equipping a frost staff make the Blade of Woe disappear.
I've not ben able thus far to find any mention of this, but I'm fairly sure that it happened. I tried all the usual remedies (restart, relog, disabling admins and/or pets), but only using a flame/shock staff made BoW reappear.
Anyone around who knows more?